Automatic injection device with audible indicator of completed injection

Abstract

The present invention relates to a device for automatic injection including a container, a piston and a piston rod coupled to the piston during the injection. A biasing element is provided for causing distal movement of the piston rod with respect to the container, with a housing receiving the container, the piston rod and the biasing element. The device further including a controlling arrangement for producing an audible indicator at the end of injection.

What is claimed is: 
     
       1. A device for automatic injection of a product into an injection site, the product being carried by a container having an open proximal end and a substantially closed distal end carrying a needle to provide an outlet port for the product from the container, and a piston provided in the container and distally movable with respect to the container, the distal movement of the piston causing the product to be expelled from the container through the needle thereby realizing the injection of said product, said device comprising:
 a piston rod intended to be coupled to said piston in the distal direction during the injection, 
 biasing means for causing distal movement of said piston rod ( 9 ;  109 ;  209 ;  309 ;  409 ) with respect to said container during the injection, 
 a housing designed for receiving at least partially said container, said piston rod and said biasing means, and 
 controlling means designed for producing an audible indicator when said piston is near said distan end of the container and the product is substantially completely expelled from the container thereby providing an indication to a user that injection of the product is completed, 
 wherein, said controlling means comprise a breakable part having a proximal end directly or indirectly coupled to said housing, and a distal end directly or indirectly coupled to said piston rod, said breakable part being caused to break at the end of injection, under the effect of the biasing means, thereby producing said audible indicator. 
 
     
     
       2. A The device according to  claim 1 , wherein said breakable part comprises a deformable wire having a proximal end and a distal end, the proximal end of said deformable wire being fixed to a fixation point located in a proximal region of said housing, said fixation point being fixed with respect to said housing during injection, and the distal end of said deformable wire being fixed to a proximal end of said piston rod, the length of said deformable wire being less than the distance separating said proximal end of said piston rod from said fixation point at the end of injection, the distal movement of said piston rod under the effect of said biasing means causing said deformable wire to break at the end of injection. 
     
     
       3. The device according to  claim 2 , wherein said wire is made of nylon or polypropylene. 
     
     
       4. The device according to  claim 1 , wherein said piston rod comprises a hollow cylinder provided with a collar at a proximal end, said breakable part comprises a rigid cable having a proximal end and a distal end, the proximal end of said rigid cable being fixed to a fixation point located in the proximal region of said housing, said fixation point being fixed with respect to said housing during injection, and the distal end of said rigid cable being slidingly received within said hollow cylinder, said distal end of said rigid cable being provided with a projection having an external diameter greater than the internal diameter of said collar, the length of said rigid cable being less than the distance separating said collar of said piston rod from said fixation point at the end of injection, the distal movement of said piston rod under the effect of said biasing means causing said rigid cable to break at the end of injection. 
     
     
       5. The device according to  claim 4 , wherein said rigid cable is made of polypropylene.